Not mentioned is the fact that when
researchers control for the effect of poverty, American test scores are near
the top in the world.

Our unspectacular overall scores are because the United
States has the second highest level of child poverty among all 34 economically
advanced countries, now roughly 25 percent, compared with high-scoring
Finland’s 5.4 percent. In some American
inner cities, the poverty rate is over 80%.

Poverty means poor nutrition, inadequate health care, and
lack of access to books, among other things. All of these negatively affect
school performance. The best teaching in the world has little effect when
students are hungry, ill, and have little or nothing to read.